2. Field of the Invention
1. This invention relates to a magnetic recording medium, and more particularly to a magnetic recording medium with improved magnetic characteristics and durability.
2. Discussion of Related Art
In order to attain the high density recording of a magnetic recording medium, a ferromagnetic thin film-type medium without a binder has been heretofore studied for practical application and practically used as a magnetic recording medium.
Ferromagnetic thin metallic films of CoNi, CoCr, etc. or thin films of such oxide as .gamma.-iron oxide or Ba ferrite have been used as the ferromagnetic thin film.
Generally, magnetic recording media based on the ferromagnetic thin metallic films have a poor corrosion resistance and have a serious problem, particularly in the case of forming thinner films. Furthermore, thin metallic film media are softer than the ferrite or other ceramics used as a head slider or core material and have the problem that flaws, once formed, grow larger.
On the other hand, the ferromagnetic oxide has a lower saturation magnetization than that of a ferromagnetic metal, and thus a thin oxide film medium has a smaller output than that of a ferromagnetic thin metallic film medium.
Furtherore, a thin oxide film medium is very hard and rigid and when the thin oxide film medium is formed on a polymer film substrate it is very liable to be damaged due to even a small bending of the medium caused during the sliding on a head. When the thin oxide film medium is formed on a rigid substrate to make a hard disk, a head crushing is liable to take place owing to the hardness of the medium.
In order to improve the mechanical durability of the so called continuous film type medium on the basis of a ferromagnetic metal film or ferromagnetic oxide film, particularly the durability during the sliding on a head, Japanese Patent Publication No. 57-3137 proposes use of a compound film prepared by making columnar ferromagnetic material grow on a non-magnetic substrate and filling gaps between the ferromagnetic columns with an organic polymer as a recording magnetic layer. However, a compound magnetic layer having a desirable coercive force as a magnetic recording medium cannot only be obtained by simultaneous vapor deposition of the organic polymer and the ferromagnetic material contrary to the disclosure of the Japanese Patent Publication.